Recently, a thought-provoking paper was released concerning what is the best and highest use of our farmland. Clean Wisconsin, a clean-energy group, looked at what automotive fuel would give the most miles traveled, ethanol from corn or solar electricity.
The implications of the study extend to the entire nation as Congress begins to grapple with the 2023 Farm Bill reauthorization.
Clean Wisconsin reviewed several peer-reviewed papers that looked at the efficiency of the corn ethanol process vs. using solar electricity to power all of Wisconsin’s needs. The results were remarkable. Wisconsin devotes 1 million acres to raising corn, much of which ends up as ethanol. Nationally, about 40% of the corn crop becomes ethanol, which is added to gasoline and has been touted as a green-energy solution.
It turns out Wisconsin needs less than a third of the land now used to grow corn to meet all of its energy needs if solar is used instead of corn. Furthermore, if all of Wisconsin’s 1 million acres of corn were converted to ethanol it would push a vehicle 10 billion miles; but, if the same land produced solar electricity, it would push a vehicle 804 billion miles.
Part of the reason for the discrepancy is that electric vehicles are inherently more efficient. Electric vehicles convert 90% of the battery charge into forward motion; internal combustion engines only convert 40% of the gasoline/ethanol into forward motion. It’s sort of like pouring 60% of that expensive gasoline you recently bought on the ground.
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However, it gets worse. Ethanol is a bit of an energy hog. Here, the authors introduced the concept of “energy return on investment,” which weighs how much energy goes to producing the product and how much to society. For ethanol, 80% of the energy goes to producing the ethanol, and only 20% goes to society to run vehicles. For solar, 12% goes to producing the electricity, and 88% of the energy is available to society. Corn is an energy-intensive crop, and ethanol requires large amounts of energy to produce. Corn production also produces large amounts of nitrous oxide from synthetic fertilizer breakdown, which is 300 times more powerful than carbon dioxide as a greenhouse gas.
All is not lost for corn farmers, though, as it turns out that ethanol can be converted into sustainable aircraft fuels with the same poor thermodynamics.
Converting cornfields to solar can also be good for farmers. The rent on the land used for solar is nearly as much as for corn, but without the work, inputs, or weather risk. The land gets a chance to rest for several decades, and it can be grazed by sheep, which provide vegetation control while also producing meat, fertilizer, and wool. Why sheep? Well, goats climb all over the solar panels, and 1,500-pound steers see them as great places to take care of big itches.
Sheep do burp methane, another greenhouse gas, but by ripping the tops off of plants they cause some of the roots to die. Roots are made of long strands of carbon-containing sugars. When soil organisms eat the dead roots, the carbon is locked into the soil, slowly building the soil over time.
Though we should still maximize solar on degraded lands like parking lots, rooftops, decommissioned landfills, and gravel pits, this paper showed that we shouldn’t be shy about using “good land” for solar. By extension, the Farm Bill should deemphasize ethanol production and emphasize more solar in agriculture.
Dr. Eric Enberg practices family medicine in West Duluth and is a member of the Northland Chapter of Citizens' Climate Lobby. He is also a member of the Duluth Climate and Energy Network and Healthcare Professionals for a Healthy Climate.
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